Field of the Invention
The present disclosure relates to the technical field of Raman spectroscopic inspection, and in particular, to a method for identifying an object using Raman spectroscopy.
Description of the Related Art
Raman spectrum is a molecule vibration spectrum, which may reflect fingerprints of molecules and may be used for inspection of a matter. The Raman spectroscopy inspects and identifies a substance by detecting Raman spectra produced by Raman scattering effects of an exciting light by an object to be inspected. The Raman spectroscopy has been widely applied in fields such as liquid security inspection, jewel detection, explosive detection, drug detection, medicine detection and the like.
The Raman spectroscopy has a problem of interference of a florescence signal in matter inspection. The Raman scattering section of a molecule is significantly smaller than its florescence scattering section. Thus, when the florescence from a molecule of an object to be detected or the florescence from a package of an object to be detected is stronger, the Raman spectrum only occupies a tiny portion of a detected signal. When the Raman spectrum collected in test is relatively weak, it may typically be enhanced by increasing an exposure time. However, in order to protect a spectroscope, the intensity of Raman spectrum collected in each test will be limited to a threshold, and the spectrum will not be displayed in entirety if its intensity exceeds the threshold. Therefore, when the florescence interference is large, the collected Raman spectroscopic signal will be too weak to identify the matter.
At present, a main method of suppressing the florescence interference is to use a laser having a long wavelength and a weak florescence effect, such as 1064 nm laser, or to add a florescence Quencher, or to use a Raman enhance technology. The Raman spectroscopic signal collected by a long wavelength laser is often very weak and thus the detection time is long. In this way, it is very difficult to be used to detect the matter having low Raman effect. The florescence Quencher may introduce a strong Raman spectroscopic signal itself, which will adversely influence the accuracy of Raman spectrum data. The Raman enhance technology generally cannot eliminate the florescence interference from packages. In practice, the florescence interference from strong florescence matter or packages is very common. Thus, research for eliminating or reducing the adverse effects of florescence in Raman spectroscopy is very significant for expanding applications of the Raman spectroscopy.